This application claims priority from Canadian Application No. 2,371,455, which was filed Feb. 11, 2002.
This invention relates generally to the field of venting devices, and in particular, to passive venting devices.
Virtually all buildings and enclosures where human activity takes place require venting of one type of another. The type of venting device employed will depend on the kind of enclosure to be vented. For example, bathrooms containing showers typically have active vents with fans to vent steam to the outdoors. Kitchens, particularly in restaurants and hotels, similarly have powered vents for removing odours, smoke and steam to the outdoors.
Other types of enclosures, such as attics and yard sheds, do not require active venting. However, such enclosures do typically require a passive vent to allow for air flow from the enclosure to the atmosphere. Such venting is required, for example, to prevent a buildup of moisture in the enclosure. Passive vents do not include a mechanism for forcing air out of the enclosure. Rather, they simply include a vent structure in the form of an air conduit which allows airflow. Passive vents are well-known and have been extensively used in the past.
An important feature of passive vents is their airflow area. The effectiveness of such a vent is related to the speed with which air can flow through the vent, and thus, to the airflow area. The more air flows through the vent, the faster moisture levels and temperature levels are equalized inside and outside the enclosure, thus preventing, for example, harmful condensation inside the enclosure.
Because passive vents simply allow air to flow in and out through an opening in the enclosure, they typically include a screen that blocks animals or unwanted objects from entering the enclosure through the opening, but still allows air flow. The presence of the screen tends to reduce airflow area because the screen elements block some of the area through which air could flow in order to prevent objects or animals from entering into the enclosure.
Passive vents may be required on a variety of different surfaces, such as level roofs or sloped roofs. In the case of steeply sloped roofs, water will flow down the slope at a high rate of speed. One problem that can arise in such a circumstance is that water flowing quickly down the sloped roof encounters the vent and splashes into the vent structure. This problem is particularly likely to occur during heavy rainfall, which would produce heavy water flow down the sloped roof. Similar heavy water flow might occur, for example, when snow and ice on the roof begin to melt. A related problem is that, during times of heavy precipitation, raindrops can hit the roof and bounce into the vent structure. Thus, for vents used on such surfaces, it is desirable to construct the vent so as to prevent water from entering the vent structure.
U.S. Pat. No. 4,903,445 discloses a roof ridge vent having flaps attached at a pivot point to allow use of the vent on roof ridges of different angles. The vent includes two screens having an ordinary sloped configuration, i.e. the screens do not extend flat across the opening in the roof, but instead slope upward away from the opening. However, this device suffers from the problem of being limited to use on roof ridge openings. It is also complex and expensive to manufacture, assemble and install.
U.S. Pat. No. 4,817,506 teaches a roof vent for disposition along a roof ridge. The vent includes a sheet-like cover having an inverted V-shaped cross-section, and a plurality of spaced partitions for supporting baffles, which baffles are also used for attaching the vent to the roof.
This device suffers from the problem of being limited to use on roof ridges. It is large and unwieldy, as well as complex and expensive to manufacture and install.
U.S. Pat. No. 6,155,008 discloses a passive venting device having an attachment flange, a vent structure and a cover for covering the vent structure. Also included is a screen for preventing objects from passing into the vent structure. Though the vent is substantially rectangular, the screen is a five-sided shape in plan view. Thus, the screen has five screen sections corresponding to the five sides of the screen. However, this screen has an ordinary sloped straight-line configuration wherein the screen extends over the vent structure opening in an upward sloped direction and in a straight line away from the roof.
Therefore, what would be desirable is a passive venting device, suitable for use at a variety of different locations on a roof, which preferably provides increased airflow to and from the enclosure being vented and is simple and inexpensive to manufacture and install.
Accordingly, the present invention is directed to a passive venting device for venting a building enclosure to an outside, the device comprising:
a base member comprising (1) a vent structure for permitting gases to pass in and out of said building enclosure through an opening in a surface of said building enclosure and through said vent structure; (2) an attachment structure connected to said vent structure for attaching said device to said surface such that said opening is in fluid communication with said vent structure; and (3) a gas-permeable screen, said screen being sized, shaped and positioned to prevent objects from passing through said vent structure, said screen having an airflow-enhancing configuration for providing greater airflow area than screens of ordinary sloped configuration; and
a cover member mountable to said base member so as to cover said vent structure and permit the free flow of gas through said vent structure;
wherein said gas-permeable screen is positioned such that, when said attachment structure is attached to said surface, all of said screen has a vertical displacement from said attachment structure.